On this page, you will find out about why the three states of matter have their particular properties. In order to understand what is going on, you have to think small. Everything is made from particles called atoms and molecules. The properties of things depend on what particles are there and how the particles are arranged.

The easiest way to imagine particles is as small balls. These particles are in constant movement.

The hotter they are, the faster they move.

This can explain freezing/melting, boiling/condensing and lots more.

It is called the Kinetic Theory of Matter. Kinetic is something to do with movement.

Solids

In solids, the particles are arranged in a regular pattern, touching each other.

They attract each other with a strong force (because they are so small and so close). This means that they cannot change places. Remember above, the particles of matter are always moving. Since they cannot change places in a solid, they simply vibrate.

A good way of thinking about this is to imagine the pupils in your class as representing the particles of a solid. When everyone is in their places, it is like a solid. Everyone moves a bit but they don't swap places.

Solids do not flow. The particles in a solid cannot change places so a solid will keep its shape (unless it is broken).

Solids cannot be compressed. Since the particles of a solid are already touching each other, they cannot be squashed any closer.

Solids can be quite strong because the particles are close which makes the forces holding each particle to its neighbour strong.

It is not possible to pass through solids without breaking them because the particles are so tightly packed and cannot move out of the way.

Remember, there are usually exceptions to most scientific rules, we all know examples of weak solids.

Liquids

In liquids, the particles are still pretty close together but not necessarily touching each other. There is no pattern. We say that they arranged randomly. They are moving about in all directions, changing places all of the time.

The forces holding the particles together in a liquid are not as strong as those in a solid. Remember, the particles are moving all of the time. In a liquid, you can see that it is possible for them to change places.

A good way of thinking about the particles in a liquid is to imagine your class in a science lab at the start or end of a practical. Everyone is still quite close together but you are all moving about, changing places. Often the pupils in a class will bump into each other at these times. This also happens in liquids!

Liquids can flow. This is because the particles can move past each other.

Liquids will not keep any shape because the particles are always moving around and changing places. They will take up the shape of the container they are in.

Liquids cannot be compressed because the particles are already very close together.

Gases

In gases, the particles are very spread out. They are moving very quickly in different directions. They are not arranged in any pattern. They are changing places all of the time.

The forces holding the particles together are very small. They are so small that they can be ignored so we say there are no forces holding them together.

Back to the class as an example. At the end of the lesson, when you leave the room, the pupils in the class all go their separate ways. You spread out round the school so you are a bit like a gas.

Gases flow. This is because the particles are always changing places with each other.

Gases spread out to fill the container. This is because they are moving very fast and there are no forces to stop them flying apart. They will be stopped by the solid walls of the container.

Gases can be compressed (squashed). This is because the particles are so far apart. They can easily be squeezed together.

Gases spring back when you stop compressing (squashing) them. As soon as you stop squeezing, they fly apart again.

Now think about this.

It is easier to walk through air than through water. It is much easier to walk through water than through a wall. You should now be able to explain why in a scientific way.

email me with the answer or if you have any questions that you need answering. Sorry, no prizes but if you are Y9 or below and your answer is detailed enough, you will get your name in the "Hall Of Fame"and receive a certificate as soon as I get it sorted.

Want to know more? Good scientists should check out several sources of information. Try this site as well: